The easy and best technique for sharpening uses Photoshop to create a high pass layer and then layer masks to control where and how much sharpening is applied. 

A high pass layer works in the same way an un sharp mask works on film: the high pass layer creates slightly blurry halos around edges in the original image, thus increasing the contrast at edges. The difference between high pass sharpening and most other methods of sharpening is that high pass sharpening does not actually adjust or change any pixels in your original image. Also, because high pass exists as a separate layer, you can adjust the layer’s Opacity and Blending Modes to control the strength of sharpening over the entire image. You can then use masks to control where sharpening is applied within the image and to make localized changes in the strength of sharpening.

Another advantage to sharpening with a high pass layer is you can save the layer with the Photoshop file and go back later and change the settings and areas where sharpening has been applied. This is a huge advantage when working with an image that you might finish for web viewing and printing, or printing on different papers. Process:

1. Evaluate the Image: First we need to evaluate the image we are going to sharpen like., where the sharpening is needed and the amount of sharpening is needed. 

2. Stamp New Layer or Duplicate Your Image Layer: Sharpening is usually the last or almost the last thing you do when preparing an image, and you want to be sure that you are applying sharpening to a finished, complete image. Therefore, before making your sharpening layer, ensure you have a duplicate layer of your completed image. To Stamp New Layer, check that all layers you want included in your final image are visible (turned on). Click on (select) your topmost layer and then stretch your fingers to use Command-Alt Shift-E/Control-Alt-Shift-E to activate the Stamp Visible command and make that stamp a new layer. 

3. Desaturate the High Pass Layer: A disadvantage to sharpening with a high pass layer is the potential for increasing or adding noise to a photo. With other sharpening tools such as Un sharp Mask, you can control noise problems with adjustments to the different values set in the tool. With the high pass option, you control noise by doing three things: Ensure your image capture is as clean as possible. This means using a tripod if not shooting at a high shutter speed, choosing the lowest ISO possible, and using the correct exposure. 

• Deal with any noise while processing your image. 

• Desaturate the high pass layer. Even when working on a colour image, the colour information in a high pass layer is irrelevant, so we’re going to remove that information right from the top to ensure that extra information doesn’t add noise. 

4. Apply the High Pass Filter: To apply the high pass filter to your sharpening layer, go to Filter > Other > High Pass. This will bring up a dialogue box with a Radius slider. You want to increase the Radius slider (increase the number of pixels affected) until the details in the image just begin to pop. You’ll find you need more Radius when you’re working with high resolution images. Don’t be surprised if you need around 10 to 20 pixels or more. Select OK 

5. Set the Layer’s Blending Mode: Change the layer’s blending mode in the blending options drop down menu to Soft Light. As you become more familiar with using high pass sharpening, experiment with Hard Light and Overlay blending modes as well 

6. Adjust the Layer Opacity: You will likely find that you now have a bit more sharpening than you need. That’s okay; starting with 100%, adjust the Layer Opacity down to get the amount of sharpening you need. Aim for an opacity that gives you the right amount of sharpening in the area of your image that needs the most sharpening. Add a layer mask by clicking on the Layer Mask icon at the bottom of your Layers window, or by going to Layer > Layer Mask.